Chemical cutting method and apparatus for use in wells



vFeb. 5, 1963 w. G. SWEETMAN CHEMICAL CUTTING METHOD AND APPARATUS FOR USE IN WELLS Filed May 16, 1958 5 Sheets-Sheet 1 W////a/77 6. Jweefman INVENTOR.

ATTORNEV Feb. 5, 1963 w. e. SWEETMAN CHEMICAL CUTTING METHOD AND APPARATUS FOR USE IN WELLS Filed May 16, 1958 5 Sheets-Sheet 2 W////0m G. Jweefman INVENTOR.

ATTORNEY.

Feb. 5, 1963 Filed May w. G. swEETMAN CHEMICAL CUTTING METHO D ANDMAPPARATUS FOR USE IN WELLS 5 Sheets-Sheet 3 8 VV////a/27 6". Jweezman INVENTOR.

ATTORNEY I Feb. 5, 1963 w. e. SWEETMAN 3, 6,

CHEMICAL CUTTING METHOD AND APPARATUS FOR USE IN WELLS Filed May 16, 1958 5 Sheets-Sheet 4 VV////am 6. J'wee fmcm INVENTOR.

ATTORNEY Feb. 5, 1963 w. G. SWEETMAN 3,075,507

CHEMICAL CUTTING METHOD AND APPARATUS FOR USE IN WELLS Filed May 16, 1958 5 Sheets-Sheet 5 W////am 6. \Sweezman INVENTOR.

ATTORNEY United States Patent 3,0 CHEMICAL CUTTING'METHOD AND APPARATUS FOR USE IN WELLS William G. Sweetman, Houston, Tex. Filed May 16, 1958, Ser. No. 735,875

30 Claims. (Cl. 166-45) This application is a eontinuation-in-part of my earlier filed applications Serial No. 288,479, filed May 1952, now abandoned and Serial No. 507,316,, filed May 9, 1955, now Patent No. 2,918,125 r This invention relates to methods and apparatus for cutting objects generally and more particularly to meth' ods and apparatus employing :a chemical cutting fluid of highly reactive incendiary character such that when brought into contact with an oxidizable object, such as a wall of a well or other object within the well, it will ignite with and burn through the object.

-The term cutting is used herein as a generic term to include cutting, severing, perforating or slotting of objects, as well as their complete disintegration. The objects referred to may be metal pipe or other well bore lining, the earth formations surrounding or forming the wall of the well bore, extraneous foreign objects, such as lost drilling tools, which may be presentin the well bore, ,or other objects of metal, stone or the like which may be in or part of the well bore.

The cutting fluids employed in accordance with the present invention are fluids which are extremely active chemically and which, when brought into contact with most oxidizable substances, react violently therewith with the generation of extremely high temperatures sulficient to melt, cut, or burn the object. Examples of such fluids are fluorine and the halogen fluorides, including such compounds as chlorine trifluoride, chlorine monofluoride, bromine trifluoride, bromine pentafluoride, iodine pentailuoridfl: and iodine heptafluoride and mixtures thereof.

Fluorine may be considered as a fixed gas under most pnactical operating conditions, since it has a very low eritical temperature, about 200 F. Chlorine trifluoride, which is a particularly eiie-ctive cutting fluid for most applications, is a volatile liquid boiling at 523 F. and may, therefore, be readily liquilied and maintained in theliquid phase by holding it under moderate pressures. The other halogen fluorides are all relatively low boiling liquids readily vaporizablein the performance of the methods of the present invention wherein these fluids will ordinarily. be applied in-the gaseous phase to the object to be cut. t

Generally stated, and in accordance with one useful application of this invention, an incendiary chemical fluid of the character described is'introducel into a w'ell in a confined body from which the fluid is caused to discharge in onefor more high velocity streams or jets by applying to the body of the fluid asuitable pressurizingmedium. Such pressurizing mediums may be hydraulic or pneumatic fluids. The pneumatic fluids may be gases generated by the ignition'of one of the various types of relatively slow-burning gun powders, or other deflagrating types of explosives, examples of which are black powders such as are usedin sporting ammunition, rocket propellant powders and the like. By appropriate selection of the ex P Si nd ri a s f e p tatis p s ssu s e l known to those skilled in the art of such explosives, the ignition and burning rates of such explosives may be ef iectively controlled to generate gases at any desired rate and volume suitable for applying the desired pressurizing forces to the confined body of the cutting fluid. Gaseous pressurizing fluids such as carbon dioxide, nitrogen and the like may be employed for applying the desired pressurizing forces to the body of the cutting fluid.

It is found that the efiiciency and speed of the cutting action of the incendiary fiuids which is obtained by the method in accordance with this invention may be greatly increased and made more effective by causing pre-ignie tion of the cutting fluid while it is being ejected from the body thereof under the high pressures applied thereto by the pressurized medium and before dis-charge from the cutting jets.

This term pro-ignition is employed herein to describe a phenomenon, the mechanism of which is largely unknown, but which constitutes a most important improvement in the primary process of this invention. It has been found that if the incendiary chemical cutting fluid, immediately prior to its discharge from the outlet passages or jets and while it is under the high pressures exerted thereon by the pressurizing medium, is brought into direct contact with certain substances, to be described in greater detail hereinafter, a form of reaction, which appears to be some presently unknown type of pre-ignition of the incendiary fluid, occurs such that the cutting eiliciency of the discharging fluid is very greatly intensified. Whether the phenomenon is catalytic or the result of a chemical reaction such as extremely rapid oxidation has not been determined but the result is, as noted, a great increase in the efficiency and speed of the cutting action of the incendiary fluid over that obtained without the use of such pre-ignition step or means. i 1

' The substances which will function effectively to produce such pre-ignition have been found-to be many and widely varied in character. In general, itappears that numerous metallic and non-metallic solid materials are effective igniters, particularly it employed in finely di vided form, as in fibrous, spongy, granular or powdered form. A preferred material is ordinary steel wool of conventional commercial grades. Glass wool is a very eti'ective igniter. Hydrocarbon materials, such as oil or grease, especially if deposited on a suitable carrier adapted to provide extended surface area for exposure to contact with-the incendiary chemical fluid, are also very effective.

Accordingly, it is a primary object of the present invention to provide a method of cutting objects by the em ploymentof an incendiary chemical fluid. f

An important object is to provide a method for cutting inside a well by the employment of an incendiary chemical fluid. I Another object is to provide a method for cutting in side a well by introducing into the well a confined body of an incendiary chemical fluid, and ejecting said fluid from said body in one or more narrow streams or jets directed against the object in the well by the action ofa pressurizing fluid applied to the body of the cutting fluid,-

An additional object is to provide a method for cutting objects by pre-igniting a highly pressurized stream of an incendiary cutting fluid and directing the pro-ignited stream against the object.

turther object is to provide a method for cutting in-,

side of a well by introducing into the well a confined body of an incendiary chemical fluid, ejecting the fluid from the body thereof in one or more narrow jets directed against the object to be cut, and pre-igniting the streams of fluid prior to contact thereof with the object.

Still another object is to provide a method of the character described wherein the presurizing medium comprises gases generated by the ignition of an explosive material.

Yet another objects is to provide a method of the character described wherein the pressurizing medium is a hydraulic fluid conducted to the cutting tool from the surface.

An additional object is to provide a method of the character described in which the pre-ignition material is a finely divided solid substance.

A more specific object is to provide a method of the character described in which the incendiary chemical fluid is a member of the class consisting esentially of fluorine and the halogen fluorides.

I have further found that in many instances it is desirable to precede the incendiary chemical fluid with another type of chemical treating fluid which is adapted to clean or otherwise prepare the surfaces of the object against which the incendiary fluid is to be projected, in order to further increase the efliciency of the cutting action of the incendiary fluid. For example, well pipes which are to be severed, perforated or otherwise cut, may, in many instances, have a coating of foreign matter, such as cement or lime, gypsum or other mineral deposit thereon which may interfere with the speed and efficiency of the cutting action of the incendiary fluid on the underlying metal surfaces. In such cases, I have found that by first applying to the surfaces coated with such foreign matter a quantity of a chemical treating fluid which is adapted to react with or dissolve such foreign matter, the cutting efficiency of the subsequently applied incendiary fluid will be greatly enhanced.

Such chemical treating fluids will ordinarily comprise one of the common mineral acids, such as hydrochloric or sulfuric acid, but may include other chemical fluids, depending generally upon the character of the deposits to be treated thereby.

Ordinarily, the treating fluid will be separately encased in the same housing in which the incendiary fluid is contained and will be ejected in advance of the incendiary fluid by a common pressurizing medium, such as the previously described explosive, the fluids being successively ejected by the pressure acting first on the body of incendiary fluid and then, by the pressure of the latter on the body of the treating fluid.

In still other instances, particularly in well perforating, it may be desirable to follow the jets of incendiary fluid forming the perforations in the earth formations with a chemical treating fluid, such as hydrochloric acid, which is reactive with the rocks comprising the earth formations, to enlarge, deepen, or clean the perforations.

In still another embodiment of this invention, the incendiary fluid may be both preceded and followed by a treating chemical, the several bodies of fluid being successively ejected from a containing housing by a common pressurizin g medium.

. Accordingly, it is another important object of this invention to provide a method for cutting inside a well by the employment of an incendiary chemical fluid and a chemical treating fluid applied successively to the objects to be cut.

A further object is to provide a method for cutting inside a well by the employment of an incendiary chemical fluid and a chemical treating fluid applied successively to the same portions of the objects to be cut under pressure from a common presurizing medium.

An additional object is the provision of a method of cutting inside a well wherein a series of chemical fluids are successively projected under pressure of a common pressurizing medium against a surface to be cut, at least one of said fluids is a member of the class consisting of fluorine and the halogen fluorides, and another of said fluids is a member of the class consisting of hydrochloric and sulfuric acids, and wherein said common pressurizing medium comprises gases generated by the ignition of an explosive material.

A further object is the provision of apparatus suitable for performing the methods in accordance with this invention.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates several embodiments of apparatus in accordance with this invention which are particularly useful for conducting the methods in accordance with this invention.

In the drawing:

FIG. 1 is a diagrammatic view, partly in section, showing a pipe severing apparatus in accordance with one embodiment of this invention installed in the well;

FIGS. 2 and 3 are views similar to FIG. 1 showing successive stages in the operation of the apparatus;

FIGS. 4A to 4F, inclusive, together constitute a longitudinal, partly sectionalview of the apparatus shown in FIGS. 1 to 3, showing the structural details thereof;

FIG. 5 is a cross-sectional view taken generally along line 55 of FIG. 4B;

FIG. 6 is a cross-sectional view taken generally along line 6-6 of FIG. 4B illustrating the discharge arrangement for performing circular severing;

FIG. 7 is a view generally similar to FIG. 1 of another embodiment in accordance with this invention;

FIG. 8 is a view generally similar to the portion of the apparatus illustrated in FIG. 4E showing a modification of the jet arrangement employed for perforating; and

FIG. 9 is a cross-sectional view taken generally along line 99 of FIG. 8.

The embodiment ilustrated in FIGS. 1 to 6, inclusive, is one in which two chemical fluids are employed, one being the incendiary chemical fluid which perform the cutting operation, and the other a treating chemical, such as hydrochloric acid, arranged, in this embodiment, to precede the incendiary cutting fluid for purpose of removing cement, gypsum scale, or the like, from the pipe to be cut.

The device here ilustrated carries a cutting head adapted to effect a severing of the pipe into which it is run.

Referring first to FIG. 1, there is shown a cutting tool, designated generally by the numeral 1, which is inserted in a string of tubing or other pipe 2, extending into a well bore B, which may be lined with the usual metal casing 3. The cutting tool comprises, in downwardly arranged succession, a pressurizing section, designated generally by the numeral 4, an anchor sub, designated generally by the numeral 5, a first or upper chemical container section, designated generally by the numeral 6, a second or lower chemical container section, designated generally by the numeral 7, an igniter section, designated generally by the numeral 8, and a discharge head section, designated generally by the numeral 9. These several sections, which are constructed of suitable strong metal, such as steel, are generally cylindrical and connected together in cnd-to-end co-axial relation to form an elongate cylindrical tool of substantialy uniform external diameter, which is adapted for insertion into the tubing string. A firing head section, designated generally by the numeral 10, is connected to the upper end of the tool and is suitably secured to a rope socket 11 of generally converttional form, which connects the upper end of the tool to a conventional flexible cable 12 which is employed for lowering and and raising the tool in the well bore B. The cable 12 may include electrical leads 13 for transmitting electric current from a suitable source (not shown) at the surface to the interior of the tool for purposes to be subsequently described.

Referring now to FIGS. 4A to 4F, inclusive, which illustrate the details of the tool, firing head section (FIG, 4A) comprises a generally cylindrical body 14 connected at its upper end to rope socket 11, and pro: vided at its lower end with an externally threaded pin member 15 for connection into a complementary internally threaded socket 16 in the upper end of pressurizing section 4. i

An electrode 17 encased in a suitable electrical insulating sleeve 1 -8 is mounted in the bore of plug 15. An electrically fired explosive initiator cap 19 is mounted in a barrel 20, which is screwed into the inner end of plug 15 and disposed in electrical contact with electrode 17. It will be understood that the opposite end of electrode 17 (not shown) will be placed in electrical contact with leads 13 by conventional contact means (not shown) positioned within rope socket 11.

Pressurizing section 4 (FIGS. 4A and 413) comprises a tubular metallic body 21 having an axial bore 22 extending entirely therethrough. The upper portion of bore 22 is adapted to receive barrel 2t) and cap'19 when head section 10 is made up with body 21. Bore 22, at a point somewhat below socket 16, is internally threaded at 23 to receive a choke bushing 24 provided with an axial choke passage 25 registering with the bore of barrel 20 and providing communication with bore 22, which is herein sometimes referred to as a pressurizing chamber. The lower end of body 21 is provided with an externally threaded pin 26 adapted to be received in an externally threaded socket 27 formed in the upper portion of anchor sub 5.

Anchor sub 5 (FIGS. 4B and 4C) comprises a generally cylindrical body 28 having a plurality of longitudinal passages 29 (three shown, see FIG. 5) of rela- .tively restricted diameter extending entirely therethrough and laterally offset from the longitudinal axis thereof, the upper ends of passages 29 communicating with the interior of socket 2'7 and thence with the interior of bore 22 in the pressurizing section. The lower ends of passages 29 communicate with the interior of an internally threadedsocket 30 formed at the lower end of body 28 and adapted for connection to the succeeding sections of the tool.

Body 23 is provided with a plurality of laterally disposed, angularly spaced cylinders 3-1, each Communicating at its inner end with one of the passages 29am at its outer end with the exterior of body 28. The outer ends of cylinders 31 are annularly enlarged to form seats 32 to receive slip elements 33 having toothed outer faces 34 adapted to grippingly engage the surrounding pipe wall when urged outwardly of body 28 against the pipe wall. Slip elements 33 are mounted on the outer ends of cylindrical shanks 35 which are slidably disposed in cylinders .31 and fitted with circumferentially arranged seal rings 36, such as conventional O .rings, whereby to form fluidtight slidable seals between shanks 35 and cylinders 31.

,Spring retainers '37 are mounted on the exterior of body 2,8 to resiliently hold the slip elements in place in cylin- :ders 31 while permitting limited outward movement there- .of. r

Upper chemical container section 6 (FIG. 4C) comprises a tubular body 40 having an enlarged axial bore therethrough forming a chamber 41 communicating at its opposite ends with upper and lower internally threaded sockets 42 and .43, respectively. The upper end of body 40 is connected to the lower end of body 28 by means of an upper connector .sub 44 having at its upper end an externally threaded pin 45 receivable in socket 30 of the anchor sub, and at its lower end an externally threaded pin 46 receivable in upper socket 42 of body 40. Upper lcon nector sub 44 has an axial bore 47 extending therethrough and communicating at its upper end with the interior of socket 30 and thence with passages 29. At

6 its lower end bore 47 is counterbored at 48, the counter: bore being internally threaded to receive a choke bushing 49 having an axial choke passage 50 therethrough providing restricted communication between bore 47 and the interior of socket 42.

A pair of shear disks 51-51 are seated in the bottoms "of sockets 42 and 43 to form rupturable fluid-tight closures for the ends of chamber 41, the shear disks being held in place by tubular jam nuts 5252, having axial through-bores 58, which are screwed into the bottoms of sockets 42 and 43 to clamp the rims of the shear disks tightly against portions of the bottoms of sockets 42 and 43 surrounding the ends of chamber 41. A centrally perforated copper washer 53 is interposed between the inner end of pin'46 and the adjacent jam nut 52.

The second or lower chemical container section 7 (FIG. 4D) is substantially identical in construction to upper container section 6, and comprises a cylindrical body 40a having an enlarged axial bore 41:; therethrough forming a chamber communicating at its opposite ends with upper and lower internally threaded sockets 42a and 43a, respectively. The upper end of body 40a is connected to the lower end of body 40 by means of a second Connector sub 55 (FIGS. 40 and 4D) having at its upper end an externally threaded pin 56 receivable in socket 43 of body 40 of the upper container, and at its lower end an externally threaded pin 57 receivable in upper socket 42a of body 40a of the lower container. Connector sub 55 has an axial bore 55a extending entirely therethrough communicating at its opposite ends with the interiors of sockets 43 and 42a, respectively.

A pair of shear disks Sla-Sla are seated in the bottoms of sockets 42a and 43a to form rupturable fluidtight closures for the ends of chamber 41a, these shear disks being held in place by tubular jam nuts 52a 52a, having axial through bores 53a, which are screwed into the bottom of sockets 42a and 43a to clamp the rims of the shear disks tightly against the portions of the bottoms of sockets 42a and 43a surrounding the ends of chamber 41a. Copper Washers 53 are interposed between the ends of pins 56 and 57 and the adjacent respectively.

Shear disks 51 and 51a are constructed of metal proportioned and otherwise designed to rupture at desired pie-determined pressures. These shear disks are desirably constructed of a metal which will not be attacked by the chemicals in chambers 41 and 41a under ordinary storjarn nuts 52 and 52a,

,age conditions. Copper is found to be particularly useful for this application, although other metals, including nickel and various alloys thereof, may be used successfully.

Igniter section 8 (FIGS. 4D and 4E) comprises a tubular body 60 having an axial through bore 61 and provided at its upper end with a threaded pin 62 receivable in socket 43a of body 40a of the lower container sectron. The upper end portion of bore 61 is enlarged to form the counterbore 63 in which is inserted a tubular sleeve 64 constructed of wire mesh which supports about its exterior a concentric layer of a suitable igniter material 65 which may be any of the various materials mentioned previously. Generally, the preferred igniter material is ordinary steel wool which is preferably impregnated or wetted with a small amount of hydrocarbon oil. The end of pin .62 is spaced from the adjacent end of jam nut 52a in socket 4311 by one of the copper washers 53. Body 60 is provided at its lower end with an externally threaded pin 66 for connection to discharge head section 9.

Discharge head section 9 (FIGS. 4E and 4F) comprises a tubular body 70 having an axial bore 71, defining a discharge chamber, communicating at its upper end with an internally threaded socket 72 adapted to receive socket 73 adapted to receive an externally threaded pin amass? 7 74 carried by the upper end of a closure plug 75 forming the lower end of the tool.

A plurality of jet passages 76 of restricted diameter extend radially through the wall of body 70 in a plane intermediate the bottoms of sockets 72 and 73 to provide communication between chamber 71 and the exterior of body 70.

Bore 71 also defines a cylinder in which is slidably mounted a piston 77 having longitudinally spaced circumferential packings 78-78, such as conventional rings, seated in the exterior surface of the piston. The longitudinal spacing of the packings is such that when the piston is in its uppermost position, illustrated in FIG. 4E, the packings will seal with the wall of cylinder 71 on opposite sides of passages 76, thereby sealing off these passages from communication with the interior of bore 71. Plug 75 has an axial cylindrical recess 79 in its upper end registering with bore 71 and of slightly larger diameter than the latter, and has suflicient depth to permit piston 77 to move downwardly therein far enough to allow the upper end of the piston to move be'ow passages 76 to thereby open communcation between passages 76 and bore 71, and to thereby place jet passages 76 in communication with the interior of the tool as a whole, as will be more fully described hereinafter. A very thin washer 79a is interposed between the bottom of socket 73 and the upper end of pin 74. The internal diameter of washer 79a is made slightly smaller than the diameter of piston 77 to provide an annular retainer 7% adapted to hold piston 77 in its upper position closing off passages 76 during ordinary handling of the tool.

The thin annular retainer 79b will be easily broken when any substantial pressure is applied to the upper end of piston 77, so it will not interfere with the downward movement of the piston during operation of the tool as will be subsequently described.

The lower end of plug 75 may be provided with an extension head 80 which carries a plurality of divergent wire fingers 81 which are adapted to serve as collar locators for lodging in the crevices or grooves formed between the ends of pipe sections which are screwed into connecting collars (FIG. 1) in order to locate the tool at a selected point in the pipe.

Chamber 22 in pressurizing section 4 will have disposed therein a suitable pressurizing medium (FIGS. 4A and 4B). The pressurizing medium comprises a body of a relatively slow-burning or deflagrating explosive material 85 of the character previously described. The body of the explosive may be in molded cylindrical form, slightly smaller in diameter than the bore of chamber 22 to allow free passage of gases about the explosive body. The latter may also be supported by a tubular spacer member 86 disposed longitudinally in chamber 22 to have one end resting on the bottom of socket 27 and supporting the body of explosive 85 on its upper end. Spacer member 86 serves to hold explosive body 85 away from the bottom of chamber 22, and is provided with a plurality of openings 87 in the wall thereof to permit free passage of gases formed by burning of explosive body 85 from chamber 22 into passages 29.

In the embodiment illustrated in FIGS. 1 to 6, chamber 41 of upper chemical container 6 will be charged with incendiary chemical fluid 88 of the general character and properties previously described. Chamber 41a of lower chemical container 7 will be charged with a suitable treating chemical 89 adapted to dissolve or otherwise remove any extraneous material from the surface of the tubing which would interfere with the cutting action of fluid 88. In this illustrative embodiment, chemical fluid 89 will be ordinary hydrochloric acid, which is adapted to dissolve limestone, and the like, which constitutes a principal ingredient of the mineral scale commonly accumulating on well pipe surfaces. This material may contain suitable inhibitors to prevent or inhibit its corrosive action on metal.

The above described device is operated in the following manner: The parts of the device will be charged with explosive material and igniter material 65, as described, and will be assembled with upper and lower chemical container sections 6 and 7, along with the sevseral connecting subs and anchor sub 5, the parts being assembled in the arrangement illustrated in FIGS. 4A to 4F, inclusive. The upper end of the tool will be con nected to firing head 10 and to rope socket 11. The structure will then be lowered into the tubing to the point at which it is to be operated, locator fingers 81 being employed to engage in a tubing collar nearest the desired location in order to fix the position of the tool.

Electric current, from any suitable and conventional source (not shown) will then be applied to leads 13 to set ofl cap 19. Flame resulting from ignition of the cap will be discharged through choke passage 25 into chamber 22 where it will ignite explosive material 85. Choke passages 25 and 50 are employed to maintain pressure in chamber 22 in order to control the burning rate of the explosive. The gases generated by the burning of explosive material 85 will flow through passages 29 and exert pressure against the inner ends of shanks 35 of the slip members sufficient to drive slips 33 outwardly into anchoring engagement with the wall of tubing 2. Choke passage 50 will also provide back pressure in bore 47 and in passages 29 to assure application of sufiicient pressure to the slips to securely anchor the tool to the pipe. This anchoring action will occur in advance of the discharge of the chemical fluids from the tool, so that the tool will be held firmly against movement, and particularly against upward thrust, resulting from the discharge and consequent chemical action of the fluids ejected from the tool. So long as pressurizing gases continue to discharge from chamber 22, the slips will remain anchored to the pipe. As soon as explosive material 85 has been consumed, or the internal pressure against the slips has been fully dissipated, retainer springs 37 will act on the outer end faces of slips 33 to urge them back into seats 32 and release the tool from the pipe so that it may be withdrawn from the well. While the pressure-actuated anchor means here described is found to be particularly effective for securely anchoring the tool against movement during operation, other well-known types of anchors, such as that shown in my aforementioned application Serial No. 507,316, may be employed.

The gases passing through choke passage 50 will flow through bore 58 in jam nut 52 and exert its pressures against the uppermost shear disk 51. It will be understood that the ignition of explosive 85 will, in a very brief time, generate sufficient gas to create a pressure against shear disk 51 which will be great enough to exceed the rupture strength of the disk. The rupture of the upper shear disk will admit the gas pressure against the body of the chemical cutting fluid 88, which will then hydraulically transmit the pressure exerted against it by the gas to the lower shear disk 51, which will then also be ruptured thereby. Upon rupture of the lower disk 51, the chemical cutting fluid will be forced through bore 55a of sub 55 and then through bore 58a of jam nut 52a where pressure of the chemical cutting fluid will be exerted against shear disk 51a, closing the upper end of chamber 41a. The pressure thus exerted against shear disk 51a will rupture shear disk 51a and admit the chemical fluid 88 into pressurizing contact with the body of chemical treating fluid 89 through which the applied pressure will be transmitted to shear disk 51a closing the lower end of chamber 41a, and this shear disk will, in turn, be ruptured by the pressure. The body of treating chemical 89, being disposed in advance of cutting fluid 88, will then be forced through igniter section 8, passing through the bore of sleeve 64 and exerting its pressure against the upper end of piston 77, forcing the latter downwardly in cylinder 71 to uncover the inner ends of discharge jet passages 76. The treating fluid will discharge from pasupon the igniter material.

sages 76 at high pressure and high velocity and will strike surrounding surfaces of the tubing, The treating chemical being reactive with the coating or scale which may be present on the tubing surfaces, will dissolve, the latter (FIG. 2) and will be immediately followed by the incendiary chemical cutting fluid 88, which on passing through sleeve 64 in contact with igniter material 65, willbe ignited thereby. Its ignition will greatly increase its pressure and temperature so that when it follows treat: ingchemical 89 through jet passages 76 (FIG. 3.), it will be under tremendous pressure and velocity, as well as at high temperature, such that when it strikes. thepipe wall opposite the ends of the jet passages, which has been cleaned by the preceding treating fluid, it will react in stantaneously with the material composing the pipe wall at a rate such as. to cause the cutting fluid to burn or out rapidly through the wall.

By the method described, pressures of any desired magnitude may be exerted upon the incendiary fluid by suitable selection of the pressurizing mediums. Pressures of many thousand pounds may be thus applied, which will be sufficient to project the streams of incendiary fluid, as well as the preceding cleaning or treating fluid, through any interventing well bore fluid-s, irrespective of their pressures, against the well wall, Whatever the initial pressures exerted on the cutting fluid may be, it is apparent that rapid build-up of pressure results not only from the increasing amounts of gas generated by the explosive pressurizing material, but also by the reaction of the cutting fluid with the igniter material before the fluid discharges from the tool.

material 65', which will permit the treating fluid to pass through the igniter material without being affected thereby, and without deleterious or inactivating efiect Ordinarily, the external diameter of discharge head sec- '-tion 9-'will be made as near as possible to the, internal diameter of the pipe or well Wall, without interfering with the free movement of the tool into. the pipe or the well, so that the chemical fluids, and particularly the incendiary fluid, will 'be required to traverse only a minimum amount Io'i intervening space before striking the well wall. Reference to the well wall is intended to include not only metal i tu-bings or casings, but other well bore linings, as well as the earth formations, themselves, which form the wall of the borehole.

The cleaning or washing action of the cleaning or treating fluid and the cutting action of the subsequently discharging incendiary fluid. do not appear to be hindered by any well fluids intervening between the discharge head and the objects against which gas fluids are directed. In deed, it appears that the discharge of the incendiary fluild through well liquids under high hydrostatic heads results in more efficient cutting action than in the absence of intervening liquids, or when under relatively low hydro- "static heads.

The time factor involved in cleaning and in cutting, in accordance With the method hereinabove described, is

j extremely short, being ordinarily of the order 'of magnimedium, such as drilling mud, water, oil and the like, may be pumped from the surface by conventional pumping equipment (not shown) to exert the desired pressurig ing force against and through the shear disks to the bodies of the chemical fluids in the tool.

Where the incendiary fluid is normally a gas, such as fluorine, chamber 41 will be charged with such gaseous fluid to any suitable and convenient pressure, for example, 300 or 400 pounds psi. The shear disks 51-51 forming the closures for the chamber will be selected to .have a strength considerably in excess of such pressure; for example, several thousand pounds p.s.i., so that the pres sure of the pressuriging medium must be built up to a point exceeding the rupture strength of the shear disks. in o d r to ap ly t desired h h p u f r d s h r the incendiary fluid, and the preceding treating fluid from the discharge head at the desired high pressure,

Where the incendiary fluid is a volatile liquid, such as orine ifluori e th n a Pr s r n ambe 41 l be relatively nominal, being determined by the vapor pressure of the fluid at the temperature of operation, and the incendiary liquid will be forced from the tool by pressure of-the pressuriging medium exceeding the bursting strength of the closure disks. At the temperatures normally exist}- ;ing in well bores, and particularly by the pre-ignition oce cnrring in bore 6 1 through contact with igniter material 65, the normally liquid cutting chemical will vaporize when ejected from the discharge head, The treating chemi Pr n the incend a y u d i l, o urse,

not be ignited and will be discharged as a liquid under hi p e u It is found, as previously indicated, that by preceding t e cu t ng flu d th the t ea i g flu as desc t e cutting efliciency of the former is greatly enhanced, and clean and complete cuts or perforations will be assured. will be n e oo h w ve a in ma y ins nc s whe e e i te nal ur a es o th p p r t e o s 9 be cut are relatively clean, the chemicaltreating fluid may be omitted entirely, in which instance, lower chemical treating section 7 may be omitted from the tool string and igniter section 8 will be connected directly to the upper incendiary chemical container section 6. Such modifications are disclosed in greater detail in the aforementioned applications Serial No. 288,479 and Serial No. 507,316.

' On the other hand, there are numerous instances, par-tic, nlarly when employing the tool of the present invention gfor perforating well pipe and surrounding earth forma tions, where it may be desirable to enlarge or clean the fperforations made by the cutting fluid inorder to improve fluid flow through the perforations. In those instances, the positions of the chemicals may be reversed; that is,

.the cutting fluid will be disposed in lower chemical container section 7 and the treating fluid in section 6. The

operation of the tool is otherwise the same as previously described.

As best seen in FIG. 6, discharge passages 76 may be arranged on relatively close angular spacing. about the discharge head so that the discharging streams of the fluids, particularly the cutting fluid, will ordinarily assume a diverging form as they emerge from the discharge passages, and will strike the pipe at points immediately adjacent to each other or in slightly over-lapping relation.

This will effectively form a substantially continuous narrow annular et of cutting fluid which will produce a complete annular cut through the wall of the pipe opposite the ends of the jet passages. The previously discharged treating fluid will similarly contact the same narrow annular section of the pipe and will thus have cleared or cleaned 218 3 annular section in advance of contact by the cutting By increasing the angular spacing between. the discharge passages 76 sufliciently to avoid close contact or o -l p o h cuttin je s, wil be iden theta ss of separate, angularly spaced perforations may be made simultaneously through the pipe or in the well wall. As illustrated particularly in FIGS. 8 and 9., body 70 is modified slightly to provide a single jet passage 76 which W lliamson 19. d r c h emer n fluid sass als hsl point on the pipe or well wall to thereby provide a single perforation therethrough. This embodiment is one which is found useful for perforating, particularly where only a single opening or perforation is desired in the well wall or pipe.

Similarly, by appropriate shaping and arrangement of the discharge passages, such as the examples disclosed in my aforementioned earlier-filed application Serial No. 288,479, cuts of any desired shape and arrangement may be made in the objects against which the cutting fluid is directed as described.

FIG. 7 illustrates. more or less diagrammatically, another modification of the method and apparatus in accordance with this invention. In this modification, three bodies of chemical fluids are arranged to be discharged successively from the tool. In this particular embodiment three chemical container sections, designated generally from top to bottom by the numerals 6a, 7a and 7b, are incorporated in the tool. Containers 6a and 7b may contain treating or cleaning fluid 89, while container 7a will contain chemical cutting fluid 88. With this embodiment, treating fluid will be ejected first from container 7b to clean the surface to be cut. This will be followed by cutting fluid from container 7:: to produce the desired cut, which may be circular severing or perforations, or other type cuts, and this, in turn, will be followed by another body of treating chemical from container 64 which will clean or enlarge the cuts made by the cutting fluid. This embodiment is found to be useful particularly in perforating, as the final chemical treatment will be advantageous for cleaning out and deepening or enlarging the perforations made by the cutting fluid in earth or rock formations. In all other respects the operation of the embodiment illustrated in FIG. 7 will be the same as previously described.

It will be evident that any number of bodies of chemical fluids of the same or different character, may be serially arranged in the tool and in any order or combination which may be found to be applicable to any particular well condition which may be encountered.

It will be understood, of course, that the quantities of both the treating chemicals and the cutting or incendiary fluids will vary with the kind and extent of the cutting to be performed. The following tables provide a number of examples showing the quantities of the materials employed in effecting severing or perforating by the method of this invention:

Pipe Severing Quantity of Chemical Type Pipe 011%, gms. BlFa, gms.

% inch Casing 1,800 2, 500 3% inch Drill Pipe- 1,020 1, 400 3 inch Tubing 730 1, 400 2% inch Tubing- 510 710 2 inch Tubing 510 710 1% inch Tubin 480 650 1% inch Tubing. 380 525 1 inch Tubing"- 310 485 inch Tubing 245 340 Combination Cleaning and severing The quantity of igniter material 65 will also be variable, depending largely upon the quantity of cutting fluid employed. When using steel wool as the igniter material. the quantities will range from about one gram to about 25 grams of commercial No. 1 grade (0.00125 strand dia.). In some instances, particularly where the larger quantities of incendiary chemical are employed, mixtures, in various ratios, of No. l and No. 3 (0.0025) grades of steel wool may be employed.

As noted, the treating chemical may be one of the conventional mineral acids, such as hydrochloric or sulfuric. The quantities and concentrations employed vary with the conditions of the surfaces or bodies in the well to be treated thereby. The acids will ordinarily contain conventional inhibitors adapted to limit reactivity of the acids to non-metallic bodies or portions of the objects to be cut.

As will be evident from the foregoing and as illustrated diagrammatically by FIGS. 1, 2, 3 and 7, the cutting apparatus disclosed herein may be described as comprising a tubular body having a passageway extending longitudinally therethrough, the passageway being interrupted at longitudinally spaced points by rupturable partitions or closure means which define one or more chambers in the passageway, each adapted to contain a confined body of a chemical fluid, and means for introducing fluid pressure at one end of the passageway whereby to rupture said cl0- sure means and forcibly eject said chemical fluid against a surface to be cut or treated thereby. Where several bodies of fluid are positioned in the tool they will be ejected from the body serially along a common flow path and will successively strike the same area of the object to be cut.

It will be understood that numerous additional alterations and modifications may be made in the details of the illustrative embodiments within the scope of the appended claims without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

l. The method of cutting an object inside a well, said object having metallic and non-metallic portions, comprising, forming a confined stream of chemical fluid in a well, said stream comprising separate bodies of two chemical fluids, one of said bodies consisting of a chemical treating fluid normally reactive substantially only with non-metallic portions of said object, and the other of said bodies comprising an incendiary cutting fluid adapted upon contact with said object to ignite with and penetrate metallic portions of the same, applying a pressurizing medium to said stream, and directing said bodies forming said stream successively against the same area of said object, whereby to cause said chemical cutting fluid to ignite with and penetrate metallic portions of said object and to cause said chemical treating fluid to react with and remove non-metallic portions of said object in said area.

2. A method according to claim 1 wherein said treating fluid is the first of said bodies directed against the object.

3. A method according to claim 1 wherein said pressurizing medium is a relatively slow-burning deflagrating type explosive.

4. A method according to claim 1 wherein said chemical treating fluid is a member of the class consisting of hydrochloric and sulfuric acids.

5. A method according to claim 1 wherein said chemical cutting fluid is a member of the class consisting of fluorine and halogen fluorides.

6. A method according to claim 1 wherein said object is a well pipe, and wherein said stream is directed against an annular section of said pipe whereby to sever the same.

7. A method according to claim 1 wherein said stream is directed against a single confined area of said object whereby to perforate the same.

8. The method of cutting an object inside a well, said object having metallic and non-metallic portions, comprising, forming a confined stream of chemical fluid in a well, said'stream comprising separate bodies of two chemi cal fluids, one'of saidbodies consisting of a chemical treating fluid normally reactive substantially only with nonmetallic portion's'of said object, and the other of said bodies comprising an incendiary cutting fluid adapted upon coritact with said object to ignite with and penetrate nietallic'por-tion's of the same, applying a pressurizing medium to said stream, directing said bodies forming said stream successively'agains't the saine area of said object, whereby to cause 'said chemical cutting fluid to ignite with and penetrate metallic portions of said-object and to cause said chemical treating fluid to react with and remove non-mctallic portions of said object in'said area, and contacting said stream in its passage toward said object with a body of a substance reactive by contact with said incendiary fluid to initiate ignition thereof before it contacts said object whereby to intensify the cutting action of said cutting fluid.

9. A niethod according to claim 8 wherein said reactive substance comprises steel wool.

10. A method according to claim 8 wherein said reactive substance comprises steel wool wetted with hydrocarbon oil.

11. The method of cutting an object inside a well, said object having metallic and non-metallic portions, comprising, introducing into the well a plurality of separately confined bodies of chemical fluids, one of said fluids being an incendiary chemical cutting fluid of the class consisting ofifluorine and halogen fluorides, at least one of the other of said fluids being a chemical treating fluid normally reactive only with non-metallic portions of the object to .be cut, and successively ejecting said fluids from their respective bodies in a common stream directed against the samearea of an object in the well whereby to cause said chemical cutting fluid to ignite with and penetrate metallic portions of said object, and to cause said chemical treating fluid to react with and remove non-metallic portions of said object in said area.

12. The method of cutting an object inside a well, said object having metallic and non-metallic portions, comprising, introducing into the well two separately confined bodies t chemical fluids, one of said fluids-being an incendiary chemical cutting fluid of the class consisting of fluorine and halogen fluorides, the other of said fluids being a chemical treating fluid normally reactive substantially only with non-metallic portions of the object to be cut, and successively ejecting first the chemical treating fluid and then said cutting fluid from their respective confined bodies into a common stream directed against the same area of an object in the well, whereby to cause said chemical treating fluid to first react with and remove from said area non-metallic portions of said object, and to thereafter cause said chemical cutting fluid to ignite with and penetrate metallic portions of said object.

13. The method of cutting an object inside a well, said object having metallic and non-metallic portions, comprising, introducing into the well a first confined body of an incendiary chemical cutting fluid consisting of a member of the class fluorine and halogen fluorides, and a second confined body of a chemical treating fluid normally reactive substantially only with non-metallic portions of the object to be cut, applying a pressurizing medium to both said bodies whereby to successively eject said fluids from their respective bodies under pressure into a common stream directed against the same area of an object to be cut, said second fluid being first ejected against said area to remove non-metallic portions of said object, and said first fluid thereafter being ejected against said area whereby to ignite with and penetrate metallic portions of said object, and contacting said first fluid in its passage from said body with a substance reactive by contact with said first fluid to initiate ignition thereof before said first fluid contacts said object.

14. A method as defined by claim 13 wherein said pressurizing medium is a relatively slow-burning deflagrating type explosive.

15. A method as defined by claim 13 wherein said reactive substance is steel wool. v

16. A method as defined by claim 13 wherein said chemical treating fluid is a member of the class consisting of hydrochloric and sulfuric acids.

17. A method as defined by claim 13 wherein said pressurizing medium is, common to both said fluids, being applied to said first body of fluid and by the latter to the second body of fluid.

18. Apparatus for cutting inside a well, comprising, a tubular casing insertable in a well and having a passageway extending longitudinally thereof, a plurality of longitudinally spaced closure members disposed along said passageway to define at least two longitudinally spaced chambers adapted to contain fluids, said closure members being openable in response to fluid pressure in said passageway to place said chambers in communication with each other, one of said chambers containing a body of an incendiary chemical cutting fluid consisting of a member of the class consisting of fluorine and halogen trifluorides, the other of said chambers containing a chemical treating fluid normally reactive with non-metallicv materials, fluid discharge passage means communicating with the passageway below the chambers, and means for applying fluid pressure in the passageway above said chambers.

19. Apparatus according to claim 18 wherein said incendiary cutting fluid is contained in the uppermost one of said two chambers and said treating fluid in the lowermost one of said two chambers.

20. Apparatus according to claim 18 wherein said treating fluid is contained in the uppermost one of said two chambers, and said incendiary cutting fluid in the lowermost one of the two chambers.

21. Apparatus according to claim 18, wherein anchor means radially projectible by said pressurizing medium are mounted in said casing above said chambers for anchoring the casing to the well wall.

22. Apparatus according to claim 18 having a body of an ignition initiating means positioned in said fluid dis charge passage means to ignite said cutting fluid prior to its discharge from said passage means.

23. Apparatus according to claim 18 wherein said closure members comprise shear disks of pre-determined breaking strength.

24. Apparatus according to claim 18 wherein said closure members comprise shear disks of predetermined breaking strength constructed of copper.

25. The method of cutting an object having metallic and non-metallic portions, comprising, forming a confined stream of chemical fluid adjacent the object, said stream comprising separate bodies of two chemical fluids, one of said bodies comprising a chemical treating fluid normally reactive substantially only with non-metallic portions of said object, and the other of said bodies comprising an incendiary cutting fluid adapted upon contact with metallic portions of said object to ignite with and penetrate the same, applying a common pressurizing medium to said stream, and directing said bodies forming said stream successively against the same area of said object, whereby to cause said cutting fluid to ignite with and penetrate metallic portions of said object and to cause said chemical cutting fluid to react with and remove nonmetallic portions of said object in said area.

26. A method according to claim 25 wherein said treating fluid is the first of said bodies directed against the object.

27. A method according to claim 25 wherein said pressurizing medium is a relatively slow-burning deflagrating type explosive.

28. A method according to claim 25 wherein said chemical treating fluid is a member of the class consisting of hydrochloric and sulfuric acids.

29. A method according to claim 25 wherein said chemi- 15 cal cutting fluid is a member of the class consisting of fluorine and halogen fluorides.

30. In a method according to claim 25, the step of con tacting said stream in its passage toward said object with a body of a substance reactive by contact with said incendiary fluid to initiate ignition thereof before it contacts said object whereby to intensify the cutting action of said cutting fluid.

References Cited in the file of this patent UNITED STATES PATENTS I 2,144,208 Van Meter; Jan. 17, 1939 v16 ONeill Nov. 17, 1942 Wagner Oct. 12, 1948 Watkins Oct. 16, 195l Dill Feb. 24, 1953 Grosse June 23, 1953 Carpenter June 8, 1954 Conrad Oct. 19, 1954 OTHER REFERENCES The Making Shaping and Treating of Steel, I t'n Ed, page 62l, 1957, United States Steel Corp. 

25. THE METHOD OF CUTTING AN OBJECT HAVING METALLIC 